1. Field of the Invention
The present invention relates to recording apparatuses and recording methods for recording signals on recording media, such as optical discs.
2. Description of the Related Art
With respect to technologies for recording and reproducing digital data, there have been data recording technologies, in which optical discs, such as a compact disc (CD) and a digital versatile disc (DVD), are used as recording media. For such optical discs, there have been two types of optical discs, one being a reproduction-dedicated type of optical discs, such as a CD, a compact disc-read only memory (CD-ROM) and a digital versatile disc-read only memory (DVD-ROM), the other one being a user-data recordable type of optical discs, such as a mini disc, a compact disc-recordable (CD-R), a compact disc-rewritable (CD-RW), a digital versatile disc-recordable (DVD-R), a digital versatile disc-rewritable (DVD-RW), a digital versatile disc+rewritable (DVD+RW) and a digital versatile disc-random access memory (DVD-RAM).
It is made possible for such a recordable type of optical discs to record user data therein by applying a recording method to optical discs, such as a magnetooptic recording method, a phase change recording method, or a pigmented coat change recording method. The pigmented coat change recording method, which is also called a write-once recording method, enables recording of data only once, but disables rewriting of the recorded data, and thus, is suitable for use in data storage and the like. In contrast, the magnetooptic recording method and the phase change recording method each enable rewriting of data, and thus, are widely used in various applications including an application for recording various kinds of content data, such as music, videos, games and application programs.
Furthermore, nowadays, realizations of optical discs each having a high storage capacity have been attempted, and a high-density optical disc, which is called a Blu-ray Disc (a trademark of Sony Corporation), has recently been developed. For example, such a high-density optical disc is capable of recording data of a size of around 23.3 GB (gigabytes) on a disc of a diameter of 12 cm in the case where recording and reproduction of data is performed under the condition in which a laser of a wavelength of 405 nm (which is a so-called blue color laser) and an object lens of an NA of 0.85 are combined therein, and a format thereof is such that a track pitch is 0.32 μm, a linear density is 0.12 μm/bit, a data block of a size of 64 KB (kilobytes) is handled as one unit of recording or reproduction of data, and a format efficiency is approximately 82%.
Further, in the case where a format thereof except a linear density is the same as that described above and the linear density is 0.112 μm/bit, such a high-density optical disc is capable of recording data of a size of around 25 GB. Further, by increasing the number of recording layers to two, it is possible to realize an optical disc having a high storage capacity of 46.6 GB or 50 GB, which is twice that of the corresponding optical disc described above. Naturally, by increasing the number of recording layers to three, four, . . . , n, it is possible to realize an optical disc having a high storage capacity resulting from multiplying 23.3 GB or 25 GB by “n”. For such a high-density optical disc, a write-once type of optical disc, which is called a Blu-ray Disc-recordable (BD-R), and a rewritable type of optical disc, which is called a Blu-ray Disc-rewritable, have been also developed.
In addition, in this specification document, in optical discs each being capable of recording user data therein, a write-once type of optical discs, such as the CD-R, the DVD-R and the BD-R, is called “a write-once disc” as a whole, and a rewritable type of optical discs, such as the CD-RW, the DVD-RW and the BD-RE, is called “a rewritable disc” as a whole.
In addition, herein, reference patent documents are provided as follows:
Japanese Unexamined Patent Application Publication No. 2004-280864; and
Japanese Unexamined Patent Application Publication No. 2007-272988